1. Field of the Invention
The present invention relates to an electrode having a gas discharge function and a plasma processing apparatus.
2. Description of the Related Art
A plasma process, such as a plasma etching process or a plasma chemical vapor deposition (CVD) process, is used to manufacture a semiconductor integrated circuit apparatus. A typical plasma processing apparatus includes an upper electrode and a lower electrode in a processing chamber, and plasmatizes a processing gas in the processing chamber by applying radio frequency power to at least one of the upper and lower electrodes.
Such a plasma processing apparatus is disclosed, for example, in Patent Reference 1.
Patent Reference 1 discloses a plasma etching device, where an upper electrode of the plasma etching device has a gas discharge function and is a composite electrode including a replaceable electrode cover member at a processing space.
In the composite electrode, a gas hole diameter of the replaceable electrode cover member is equal to or smaller than a gas hole diameter of an electrode cover member at a base. The gas hole diameter of the replaceable electrode cover member is smaller so that the electrode cover member at the base is not damaged by plasma.
However, according to such a composite electrode, since the gas hole diameter of the replaceable electrode cover member is smaller than the gas hole diameter of the electrode cover member at the base, a differential pressure (stress) may be applied to the replaceable electrode cover member during gas discharge. When the differential pressure is applied, the replaceable electrode cover member may break, and thus in reality, a thickness of the replaceable electrode cover member is increased or a maximum gas flow rate is limited so as to suppress “break of an electrode cover member”. Accordingly, an electrode cover member cannot be thinned, and thus reduction of manufacturing costs is hindered and the degree of freedom related to the maximum gas flow rate is limited.
Also, a gas discharge rate introduced in a processing chamber is determined by a gas hole of an electrode cover member at a processing space, which has smaller conductance than a gas hole of a base material. However, the gas hole at the processing space is damaged by plasma. When the gas hole is damaged and is widened in a horn shape, the gas discharge rate is changed. In other words, in a configuration where a gas hole of an electrode cover member at a processing space determines a gas discharge rate, a gas behavior changes as time passes in the processing chamber during gas introduction.
3. Prior Art Reference    (Patent Reference 1) Japanese Laid-Open Patent Publication No. 2006-287162